Fix template error for elixir-enabled applications.

[slezakattack]

Hello, I have an Elixir-based app that is pulling ejabberd as a dependency and noticed when I run the app as a release, the console logs are missing the messages:

 2024-07-12 14:17:24.108891-06:00 [info]
 2024-07-12 14:17:24.142699-06:00 [info]
 2024-07-12 14:17:24.170040-06:00 [info]
 2024-07-12 14:17:24.172795-06:00 [info]
 2024-07-12 14:17:24.225542-06:00 [info]
 2024-07-12 14:17:24.225665-06:00 [warning]

I realized that there is a bug in the template that uses message when it needs to be msg (as seen in the Erlang documentation https://www.erlang.org/doc/apps/kernel/logger_formatter#t:template/0)

After making this change, I get the following, correct logs:

 2024-07-12 14:45:59.809550-06:00 [info] Loading configuration from ejabberd.yml
 2024-07-12 14:45:59.842689-06:00 [info] Configuration loaded successfully
 2024-07-12 14:45:59.867775-06:00 [info] Got no NOTIFY_SOCKET, notifications disabled
 2024-07-12 14:45:59.870429-06:00 [info] Building language translation cache
 2024-07-12 14:45:59.920871-06:00 [info] Loading modules for localhost
 2024-07-12 14:45:59.920980-06:00 [warning] Mnesia backend for mod_mam is not recommended: it's limited to 2GB and often gets corrupted when reaching this limit. SQL backend is recommended. Namely, for small servers SQLite is a preferred choice because it's very easy to configure.

[coveralls]

coverage: 32.969% (-0.02%) from 32.987%
when pulling 090a8e3 on slezakattack:elixir_logger
into 101cce0 on processone:master.

[badlop]

Thanks for fixing it!

[badlop]

Bad news: after applying your patch, ejabberd fails to log messages when used stand-alone. Apparently, ejabberd uses Elixir's Logger.Formatter, which uses message as originally implemented, not msg as used by Erlang/OTP's logger.

I've done a very simple test with ejabberd 24.06, and your patch is not needed at all:

1. Create an app

mix new myapp
cd myapp
vim mix.exs

2. Set ejabberd as a dependency:

  defp deps do
    [
      {:ejabberd, "~> 24.6"},
    ]
  end

3. Get dependencies, compile, and setup ejabberd configuration file:

mix deps.get
mix compile
wget https://raw.githubusercontent.com/processone/ejabberd/master/ejabberd.yml.example
mv ejabberd.yml.example ejabberd.yml

4. Finally start a console, ejabberd 24.6 starts and logs correctly

mix
2024-07-15 12:26:35.493 [info] Loading configuration from ejabberd.yml
2024-07-15 12:26:35.985 [info] Creating Mnesia ram table 'route'
...
2024-07-15 12:26:36.400 [info] ejabberd 24.6.0 is started in the node :nonode@nohost in 0.93s
2024-07-15 12:26:36.429 [info] Start accepting TLS connections at [::]:5223 for :ejabberd_c2s
...

I'll have to revert this PR as it is now.

I have an Elixir-based app that is pulling ejabberd as a dependency

How did you integrate ejabberd into your elixir application? Maybe your application, or some dependency, is changing the logger configuration from Elixir's one to OTP's one?

Can you provide a minimal example that allows to reproduce your problem?

It would be great if your specific scenario can be detected when ejabberd is starting in console_template, and set the proper log template strings for your specific case.

[slezakattack]

Can you provide a minimal example that allows to reproduce your problem?

Yes, if you take the example you currently have and instead do

mix release
./_build/dev/rel/myapp/bin/myapp start

This would reproduce the issue. It only seems to occur during a release which makes me wonder if it has something to do with application startup order (i.e. erlang logger starts before Elixir.Logger?). I'm new to Elixir so I'm not entirely sure how it comes together along with the Erlang libraries..

[badlop]

Aha! Now I could reproduce the problem.

I've added a small fix that works great for me, both in standard ejabberd start methods, and also works using the method you described.

Can you try it and confirm it's fixed? Either apply the change yourself, or download the raw file and replace it.
https://raw.githubusercontent.com/badlop/ejabberd/dependabot/src/ejabberd_logger.erl

[slezakattack]

Awesome, yes just tested this out and it seems to work. Thank you!